[ntp:questions] Reasons of NTP not to use GPS source
Igor Pavlov
pavlov.ig at gmail.com
Tue Sep 17 08:05:42 UTC 2013
Thanks, Brian.
I'll do all these things.
Now will try to fix problem with PPS: it's level 3.3V, and serial port
seems to not recognising such low level.
Now playing with time2 parameter and my GPS now stoped getting "x".
I can't understant one thing.
Should system time be fluently corrected by NTP so in some term offset of
active ("*") source would be close to 0?
2013/9/17 Brian Inglis <Brian.Inglis at systematicsw.ab.ca>
> On 2013-09-16 01:00, Igor Pavlov wrote:
>
>> Hi!
>>
>> I am using GPS-receiver based on Geos-1m chip (
>> http://www.geostar-navigation.**com/en/navigation_05.html<http://www.geostar-navigation.com/en/navigation_05.html>
>> )
>>
>> I connected it to serial port and configured NTP.
>> It becomes unused by NTP: when do ntpq -p reuest ti puts "x" near
>> "GPS_NMEA(1)" record.
>>
>> What reasons can be for this?
>>
>> Example of "ntpq -p" output
>>
>> remote refid st t when poll reach delay offset
>> jitter
>> ==============================**==============================**
>> ==================
>> xGPS_NMEA(1) .GPS. 0 l 14 16 377 0.000 -303.07
>> 4.292
>> *stratum1.net .PPS. 1 u 62 64 377 62.800 -68.052
>> 43.693
>> +dl120g7.naviteh 194.190.168.1 2 u 58 64 377 30.151 -100.04
>> 52.432
>> +89.221.207.113 192.36.133.25 2 u - 64 377 10.006 -105.88
>> 64.279
>>
>
> See David Taylor's pages at
> http://www.satsignal.eu/ntp/**NTP-on-Windows-serial-port.**html<http://www.satsignal.eu/ntp/NTP-on-Windows-serial-port.html>
> and linked pages at top for a lot of details about setup, but keep
> everything really simple to start, then change one thing at a time after
> running for a while and checking the results.
>
> Check your GPS comms and config using the supplied setup software:
> are you seeing NMEA output at your selected 115.2kbps?
> which sentences $GPRMC, etc.?
> has your receiver completed its initial survey and is it reporting Active,
> and reasonable mode, position, altitude, UTC date and time in sentence
> $GPRMC?
> how many satellites is your receiver tracking to what precision in
> sentences $GPGGA, $GPGSA, $GPGSV?
> is your receiver set to 1Hz PPS rather than 5Hz updates?
> is PPS toggling DCD high for about 100ms at the start of ecah second?
> Note that Windows recognizes only low to high DCD transitions as PPS.
>
> If your mouse cursor starts jumping around, unplug your RS232 cable,
> *disable* the Windows mouse driver which just got loaded on your serial
> port, plug in your RS232 cable, and restart if required.
>
> If all that looks good, next try disabling everything but PPS and $GPRMC
> sentence output from your receiver config, and use only your server
> 127.127.20.n line, without any fudge settings, plus your backup Internet
> servers, in ntp.conf.
> Then restart NTP and see if ntp.log shows something like:
> ...
> 14 Aug 12:50:38 ntpd[####]: GPS_NMEA(#) serial /dev/gps# open at 4800 bps
> 14 Aug 12:50:38 ntpd[####]: GPS_NMEA(#) 8011 81 mobilize assoc #####
> ...
> 14 Aug 12:50:39 ntpd[####]: GPS_NMEA(#) 802b 8b clock_event clk_no_reply
> 14 Aug 12:50:39 ntpd[####]: Using user-mode PPS timestamp for GPS_NMEA(#)
> ...
> 14 Aug 12:50:57 ntpd[####]: GPS_NMEA(#) 8034 84 reachable
> 14 Aug 12:50:57 ntpd[####]: GPS_NMEA(#) 904a 8a sys_peer
> ...
> Now ntpq -p should show * beside your GPS_NMEA(#) entry:
>
> remote refid st t when poll reach delay offset
> jitter
> ==============================**==============================**
> ==================
> *GPS_NMEA(#) .GPS. 0 l 12 16 377 0.000 -0.011
> 0.021
> and if you defined statsdir ... and statistics clockstats in ntp.conf you
> should see entries in clockstats.yyyymmdd like:
> 56512 7.123 127.127.20.# ...
> ...$GPRMC,000006,A,5108.####,**N,11411.####,W,000.0,000.0,**
> 080813,014.7,E,D*0F
>
> If nothing seems to be working, try restarting the NTP service - at times
> it seems to have issues getting going properly in various ways.
>
>
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--
Игорь Павлов
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